I have a Lightsail instance running CentOS 7 and I would like to allow pinging to the instance from the outside. I couldn't find anything in the instance firewall settings.
I have tried running the following commands inside:
$ sudo iptables -A INPUT -p icmp --icmp-type 8 -s 0/0 -d $SERVER_IP -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
$ sudo iptables -A OUTPUT -p icmp --icmp-type 0 -s $SERVER_IP -d 0/0 -m state --state ESTABLISHED,RELATED -j ACCEPT
Unfortunately these commands did not fix the problem. I suspect it's being blocked at the Lightsail-firewall layer. Is there a way to allow ICMP from outside?
Best Answer
Ping doesn't use TCP, it uses ICMP, a different protocol. If you can't add the ICMP protocol to the Lighsail firewall then you can't ping the instance. This wasn't possible in 2019, and I don't think that's changed yet.